Endocrine Abstracts

JOINT207

Introduction: With increasing cases of osteoporosis in children and adolescents, the need for timely diagnosis, management, and follow-up has become important. In adults, the use of bone turnover markers (BTMs) to monitor anti-osteoporotic treatments has been studied and is being recommended. However, how BTMs can be used in children and adolescents with osteoporosis is not fully known, as well as its possible use as diagnostic criteria and/or as predictors of fracture risk. This study aimed to determine whether BTMs, particularly bone-specific alkaline phosphatase (BsALP) and C-telopeptide of collagen type 1 (CTx), accurately reflect bone mineral density (BMD).

Methods: In this retrospective study, 280 post puberty males, aged 12.5-18 years old, and females, aged 10.5-18 years old, who were previously diagnosed with hemato-oncologic, rheumatoid, gastrointestinal, and endocrinologic diseases at a single tertiary care center were reviewed. The association between the lumbar spine bone mineral density (LSBMD) Z-scores and BTMs, such as BsALP and CTx, were assessed.

Results: Of the 280 patients, 95 were male (33.9%), and the mean age was 15.4±2.07 years. The mean LSBMD Z-score was -0.52±1.23, with 61.4% being ≤0, 34.6% being ≤-1.0, 13.6% being ≤-2.0, and 3.2% being ≤-3.0. With multivariate regression analysis, LSBMD Z-scores and BsALP showed a negative correlation with p<0.007, while CTx was not statistically significant. The logistic regression models showed that after adjusting for underlying diseases and sex, as BsALP increased, the probability of LSBMD Z-score being ≤-2 increased with an odd ratio of 1.043 (p=0.048). When comparing BTMs with vertebral fracture while adjusting for underlying diseases and sex, as BsALP increased, the probability of vertebral fracture increased with an odd ratio of 1.035 (p=0.005). When the same comparison was made with CTx, the odd ratios of LSBMD Z-score being ≤-2 and with the presence of vertebral fracture were 0.419 and 1.001, respectively (p=0.156, 0.997), which were not statistically significant.

Conclusion: BTMs change during growth as a function of age and sex; thus, comparing BTMs directly with LSBMD without any adjustments will not give any correlation in children. This study suggest that BsALP can be used as a complementary tool to evaluate secondary osteoporosis in children and adolescents if adjustments for underlying disease and sex are made. However, further studies with a larger sample size are required to adjust for age, which will better reflect the characteristics of pediatric patients.